Ultra low frequency ballistocardiograms (Bcg) and transcutaneous carotid artery pulse recordings (CP) will be made on patients of the Multiple Risk Factor Intervention Trial (MRFIT). Three clinical centers of MRFIT with 2100 patients and the Coordinating Center are involved in this ancillary study. Bcg and CP are recorded on magnetic tape cassettes in standardized format controlled by a data encoder developed by the applicant. Cassettes are then mailed to the applicants' laboratory for analysis by digital computer. Analog recording on the cassettes are converted to digital time series on industry compatible nine track digital magnetic tape. This step is carried out on a specialized digital tape recorder. Data from these "first pass" digital tapes are then edited to produce "second pass" archive tape with ideal properties for further processing. The editing procedure is accomplished on large scale computers of the main institutional computer center. Digital time series of Bcg and CP are then analyzed by a record reading program in the same machine. Standardized objective measurements of Bcg and CP obtained in this way will then be employed in cross-sectional analyses and multivariate prognostic calculations. Bcg and CP are expected to demonstrate response to interventions and add important independent contributions to known predictive power of established risk factors for coronary heart disease.